This invention relates to engine exhaust driven turbochargers and more particularly to a conically jointed rotor for a turbocharger.
It is known in the art relating to exhaust driven engine turbochargers to provide a rotor including a turbine wheel and a compressor wheel connected by a shaft for rotation together about an axis. Various types of connecting means have been provided for aligning and connecting the wheels and the shaft for axial rotation. The connecting means for the compressor impeller wheel and the turbine wheel relative to the shaft are important because the rotor must be disassembled after balancing in order to assemble the rotor into the turbocharger. Upon reassembly of the rotor, the repeat balance must preserve the original balance as far as possible without actually rebalancing the rotor in the turbocharger assembly. Connecting means that allow separation and reassembly of the components without changing the balance are therefore desired.
The present invention provides novel connecting means for aligning or centering the compressor and turbine wheels on the axis of the connecting shaft with the capability of simple and repeatable reassembly. The connecting means include two pairs of non-locking cones, one pair connecting each of the wheels with the shaft. Each of the cone pairs has an external cone and an internal cone, both centered on the axis and drivingly engaging one another. In preferred embodiments, the external cones are connected with the wheels and the internal cones are formed in the connecting shaft. The external cones may be integral with an adapter fixed, for example, to the aluminum compressor wheel, or they may be formed integral with the wheel, as is the case with the high temperature turbine wheel. The adapter or a separate sleeve may provide an oil sealing surface. The shaft includes spaced bearing journals for supporting the rotor and at least one thrust reaction surface for axially positioning the rotor. The rotor elements are held in assembly by a threaded bolt that extends through the compressor wheel and the shaft and engages threads in the turbine wheel cone portion. Alternative securing arrangements may be provided if desired.
Alternative embodiments of connecting means combine the non-locking cones with radially engaging shoulders and abutments that share the torque transmitting loads with the non-locking cones and provide additional rotational stability.
These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings.